L20 Localisation of Cerebral Function Flashcards Preview

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Flashcards in L20 Localisation of Cerebral Function Deck (23):
1

Learning Outcomes (for general perusal)

  1. Understand why the lobes of the brain are named as they are
  2. Have some understanding of where and how different functions including language interpretation and production are processed
  3. Have some understanding of the principles of PET imaging and functional MRI

2

What is the pattern of speaking a heard word

Primary Auditory Area

Wernicke's Area

Articulate Fasciculus 

Broca's Area

Motor Cortex

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3

What is the pattern of speaking a written word?

Primary Visual Cortex

Angular Gyrus 

Wernicke's Area

Broca's Area

Motor Cortex

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4

What is dysphasia?

 

What is aphasia?

impairment of language caused by brain damage

 

loss of language caused by brain damage

5

What are the elements of speak and their relevant impairments?

  • Phonation - Dysphonia 
  • Articulation - Dysarthria
  • Language Production - Dysphasia

6

How are words articulated?

 

What are the sites of control of articulation?

movements of lips, tongue, palate, mouth

 

  • higher centres
  •   brain stem
  •   peripheral nerves
  •   neuro-muscular junction
  •   muscles

7

What is phonation?

 

What are the sites of control?

Vibration of the vocal cords

higher centres

  brain stem

  peripheral nerves

  neuro-muscular junction

  muscles

  vocal cords

8

What are the difficulties Dysphagia

Classifications
Syndromes

Overlap

Speech not encoded in identical sites

Philosophical concepts

9

Outline Geschwind’s Theories (1967)

  • Various staging posts in language pathway with coding and analysis of signals.
  • Each staging post has a distinct localisation and function.
  • The type of speech disturbance changes from area to area of the brain.

10

How is Dysphasia tested for?

  1. Spontaneous conversional speech
  2. Comprehension
  3. Repetition
  4. Naming
  5. Reading
  6. Spelled word recognition
  7. Writing

11

Testing for Dysphasia

What are the different characteristics of spontaneous conversational speech?

Melodic line

Phrase length

Articulation

Grammatical form

Paraphasias

Word finding

12

Testing for Dysphasia

How is comprehension tested?

Yes – no

Auditory word recognition

Sequential commands

13

Testing for Dysphasia

How is repetition assessed?

Numbers

Words

Sentences

14

Testing for Dysphasia

How is naming assessed?

Objects

Word fluency

Sentence completion

Responsive speech

15

Testing for Dysphasia

How is reading assessed?

Sentences

Words

Word-pictures

16

  1. What is the overall language area divided into?
  2. What do structural lesions in the peri-slyvian area produce?
  3. What does pathology involving the border zone area produce?

  1. 2 clinically distinct areas: a central peri- sylvian area, and an outer border area
  2. repetition defects
  3. aphasia with retained repetition ability 

17

18

Representation of areas that participate in clinically distinct comprehension tasks

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R = Reception

P = Perception

Both in temporal lobe and overlap

SE = Semantic Area

SY = Syntactical and Sequencing Activities

19

What are the Right and Left Hemisphere's involvement in...

  1. Gestural (motor) language
  2. Prosodic (vocal) language
    1. Rhythm 
    2. Inflection
    3. Timbre
    4. Melody
  3. Semantic (meaningful language)
    1. Verbal meaning 
    2. Concept formation
    3. Visual Imagery 
  4. Syntactic (relational language)
    1. Sequencing 
    2. Relationships

  1. Both participate
  2. Prosodic
    1. L Dominates
    2. Both participate
    3. Both Participate
    4. R dominates
  3. Semantic
    1. L Dominates
    2. Both Participates
    3. R Dominates
  4. Syntactic
    1. L Dominates
    2. L Dominates

 

20

What sort of dysphasia will a lesion in the ANT language area give?

 

What sort of dysphasia will a lesion in the POST language area give?

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Non-fluent

 

 

Fluent

21

Give the characterisics of 

Non-fluent Dysphasia 

 

 

Fluent Dysphasia

Non-Fluent

  • Sparse quantity of output
  • Considerable effort in production
  • Dysarthric articulation 
  • Short Phrase length (1/2 words)
  • Abnormal prosody 
  • Agrammatism 
  • Normal or more content words
  • Paraphasia  is uncommon

Fluent

  • Normal quantity of output, effort in production, articulation, phrase length, prosody, grammatical structures
  • Content words often omitted
  • Paraphasia common (both literal and semantic)
    • production of unintended syllables, words, or phrases during the effort to speak.

 

22

What are the principles of PET imaging?

 

(in this picture, fluroglucose was used)

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Positron Emission Tomography

  •  is a test that uses a special type of camera and a tracer (radioactive chemical) to look at organs in the body. The tracer usually is a special form of a substance (such as glucose) that collects in cells that are using a lot of energy, such as cancer cells.
  • is a nuclear medicine, functional imaging technique that produces a three-dimensional image of functional processes in the body. The system detects pairs of gamma rays emitted indirectly by a positron-emitting radionuclide (tracer), which is introduced into the body on a biologically active molecule. Three-dimensional images of tracer concentration within the body are then constructed by computer analysis. In modern PET-CT scanners, three dimensional imaging is often accomplished with the aid of a CT X-ray scan performed on the patient during the same session, in the same machine.

    If the biologically active molecule chosen for PET is fluorodeoxyglucose (FDG), an analogue of glucose, the concentrations of tracer imaged will indicate tissue metabolic activity as it corresponds to the regional glucose uptake. Use of this tracer to explore the possibility of cancer metastasis (i.e., spreading to other sites) is the most common type of PET scan in standard medical care (90% of current scans). However, on a minority basis, many other radioactive tracers are used in PET to image the tissue concentration of other types of molecules of interest. One of the disadvantages of PET scanners is their operating cost

23

What are the principles of functional MRI imaging?

 

False fonts, letter strings, words (words most likely to produce stimulation)

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Functional Magnetic Resonance Imaging

  • measures brain activity by detecting changes associated with blood flow. Relies on the fact cerebral blood flow and neuronal activation are coupled. When an area of the brain is in use, blood flow to that region also increases
  • The primary form of fMRI uses the blood-oxygen-level dependent (BOLD) contrast - specialized brain and body scan used to map neural activity in the brain or spinal cord of humans or other animals by imaging the change in blood flow (hemodynamic response) related to energy use by brain cells
  •  fMRI has come to dominate brain mapping research because it does not require people to undergo shots, surgery, or to ingest substances, or be exposed to ionising radiation, etc
  •  procedure is similar to MRI but uses the change in magnetization between oxygen-rich and oxygen-poor blood as its basic measure
  • Physicians use fMRI to assess how risky brain surgery or similar invasive treatment is for a patient and to learn how a normal, diseased or injured brain is functioning. They map the brain with fMRI to identify regions linked to critical functions such as speaking, moving, sensing, or planning. This is useful to plan for surgery and radiation therapy of the brain. Clinicians also use fMRI to anatomically map the brain and detect the effects of tumors, stroke, head and brain injury, or diseases such as Alzheimer's.

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